It's all about the fuel and fuel load.
This C172 had a full fuel load (15 mins earlier) and hit a powerline; it burnt out the tanks and fuselage as you can see, but agreed if it was composite it likely would have burnt out completely, but either way you don't stand a chance in the cockpit.
http://images.theage.com.au/2008/12/...x300-200x0.jpg